To aid the understanding of tumor cell lysis by cytotoxic T lymphocytes (CTLs), studies will be carried out on model systems in which CTLs are specific for a glycoprotein (G) of vesicular stomatitis virus (VSV) or for allogeneic histocompatibility antigens. The susceptibility of various VSV-infected targets to lysis will be correlated with the extent to which G and H-2 molecules are associated on the target cell surface. Covalently joined H-2 and G molecules, prepared by a crosslinking reagent, will also be tested for their ability to stimulate the development of CTLs. In other studies, the removal of Lyt-2,3 differentiation antigens are being examined for the effects on different stages of CTL activity. In a second line of study variability of lambda light chains of the mouse will be analyzed. Chains of the lambda2 type will be sequenced, especially in the 3rd hypervariable and 4th framework (J) region. Chains of the lambda3 type will be sequenced to determine whether they share V and J genes with lambda2, or whether they are encoded by their own unique Vlambda3 and Jlambda3 genes.